Employee stock option dilution

Stock option dilution — what new rounds do to your stake

Every funding round dilutes existing shareholders. The company issues new shares to investors (and usually expands the option pool), and your percentage of the company shrinks. Understanding the math matters for negotiating your grant, evaluating job offers, and deciding whether to early-exercise options.

Two kinds of dilution

Investor dilution: New shares issued to investors in exchange for capital. Post-money = pre-money + raise. Investor's ownership = raise / post-money. Existing shareholders dilute proportionally.

Option pool dilution: Companies expand the option pool pre-round (so new investors don't dilute immediately). The increase comes from existing shareholders. A 10% pool top-up on 10M shares adds 1.11M new option pool shares.

The math of a Series A

Company starts with:

• 10M fully-diluted shares
• $20M pre-money valuation ($2 / share)
• You own 50,000 shares = 0.5%

Series A raise:

• Raise: $5M at $20M pre-money = $25M post-money
• New option pool: 10% of post-money, created pre-close = 1.11M new pool shares from existing holders
• New investor shares: $5M / $2 = 2.5M shares
• Total post: 10M + 1.11M + 2.5M = 13.61M shares

Your ownership: 50,000 / 13,610,000 = 0.37%. Your ownership fell from 0.5% to 0.37% (25% dilution). Your share value rose from 50k × $2 = $100k to 50k × $2 = $100k (same — new shares priced at the round price). But now, if the company grows to $200M, your 0.37% = $740k. You took dilution but got valuation increase.

Founder dilution over rounds

Typical founder ownership path (2 cofounders splitting 50/50 initially):

• Day 1: 50% each
• Seed (20% dilution): 40% each
• Series A (25% dilution): 30% each
• Series B (20% dilution): 24% each
• Series C (15% dilution): 20.4% each
• Series D (10% dilution): 18.4% each
• IPO: ~15–18% each

Founder ownership at IPO is typically 10–30% combined, with top founders (Zuckerberg at Facebook, Collison brothers at Stripe) above 25% because they raised less or at higher valuations per round.

Employee dilution

Employees are hit hardest by cumulative dilution because:

• Option pool dilution happens pre-money, so the pool gets smaller as rounds progress
• Grant sizes shrink as share price rises (company can't afford $500k grants at late stage)
• Early-employee grants take the full brunt of every round

An employee #15 at a seed-stage company might get 0.5% (50,000 shares of 10M). By Series D, that's ~0.15% through cumulative dilution. At $1B IPO valuation, that's $1.5M pre-tax — substantial but not the lottery ticket early-stage employees sometimes expect.

How to minimize dilution impact

1. Negotiate option pool timing: Push for post-money pool creation instead of pre-money. Splits dilution between existing and new investors, saving existing holders ~50% of pool dilution.
2. Raise at higher valuations: Same dollar raise, higher pre-money = less dilution. Don't leave money on the table on valuation.
3. Raise less: Obvious — smaller rounds dilute less. Trade-off against runway.
4. Participate pro-rata: Existing investors can buy their share of new rounds to maintain ownership. Super-pro-rata rights let them buy more.
5. Anti-dilution provisions: Preferred shareholders often have weighted-average or full-ratchet anti-dilution that converts at lower price in down rounds. Common shareholders (employees) don't get this protection.

Calculating your offer's real value

When evaluating an equity grant, ask:

• Current number of shares AND current total fully-diluted shares (to get percentage)
• Current per-share FMV (409A value)
• Company's most recent preferred price (the valuation investors paid)
• Strike price
• Vesting schedule (4-year 1-year cliff standard)

Then model at a realistic exit: if company goes from current $100M valuation to $1B exit, your shares would be worth ~10x their strike-price paper value today. Adjust for further dilution (multiply by 0.7–0.8 for cumulative dilution from 2–3 more rounds before exit).